Knife-mounting means for slitting shear



March 9, 1965 M. v. HAMILTON 3,172,326

KNIFE-MOUNTING MEANS FOR SLITTING SHEAR Filed Aug. 29', 1962 INVENTOR MERRILL l HAMILTON A frame United States Patent O peel 3,172,326 KNIFE-MOUNTING MEANS FOR SLITTING SHEAR Merrill V. Hamilton, Gary, Ind., assignorto United States Steel Corporation, a corporation oflflew Jersey Filed Aug. 29, 1962, Ser. No. 220,220 1 Claim. (Cl. 83-665) This invention relates generally to mounting devices and, more particularly, to devices for mounting annular slitter knives on arbors.

It has been a common prior art practice to utilize a threaded shaft for the mounting of slitter knives. A first nut was threaded onto the shaft the required distance to locate the slitter knife, the slitter knife was then keyed onto the shaft against this nut, and a second nut threaded onto the shaft and tightened against the knife to hold it in place. This type of mounting has at least one very serious drawback. When the shaft is rotated one of the nuts will tend to tighten against the knife, but the other nut will tend to loosen away from the knife. The result was that the knife was not securely held and would tend to gradually move axially on the shaft away from its preselected position, the direction of movement depending upon the hand of the threads and the direction of rotation of the arbor.

It is therefore a principal object of this invention to provide a device for mounting an annular member on an arbor which will prevent axial movement of the member when the arbor is rotated.

An additional object of this invention is to provide a device which will permit facile mounting and positioning of an annular member on an arbor and will maintain the member tightly and exactly positioned when the arbor is rotated.

A more specific object of this invention is the provision of a device for mounting an annular slitter knife on an arbor which utilizes threads so positioned that nuts mounted on the threads will tighten against the knife from opposite sides thereof upon rotation of the arbor.

Other objects and advantages of the invention will become apparent from the following description and accompanying drawing, in which:

FIGURE 1 is an elevational view partially in section of a pair of slitter knives mounted on arbors according to this invention;

FIGURE 2 is a sectional view looking in the direction of line IIII of FIGURE 1; and

FIGURE 3 is a sectional view looking in the direction of line III1II of FIGURE 1.

Referring now to the drawing, and particularly to FIGURE 1, a pair of slitter knives 16 are shown mounted on arbors 12 in a position for slitting or trimming sheet material. The arbors 12 are rotated in opposite directions, and the sheet, as it passes between the slitter knives 1%, is sheared by the coaction of the knives. The mounting of both of the knives on their respective arbors is almost identical so only the upper one will be described.

The arbor 12 is provided with a plurality of circumferential grooves 14 extending therearound. These grooves are not threads but each is a separate and distinct groove, the grooves being separated by lands 16. These grooves 14 provide for the mounting of the slitter knife 19 at any selected position axially along the arbor.

A pair of annular split rings 20a and 205 are provided to locate the slitter knife on the arbor. The rings 20a and 20b are identical structurally and are designated by a and b to simplify and clarify the description of their positions when assembled on the arbor 12. Each split ring 20a and 20b has a pair of internally directed lands 22, a key slot 24, and each is externally threaded at 26.

In order to mount the slitter knife 10, the split ring 20a is positioned on the arbor 12 as seen in FIGURE 1 with the lands 22 engaging a pair of adjacent grooves 14. The halves of the split ring 20a are held in alignment by a pair of dowel pins 28 to maintain the continuity of the external threads 26. A nut 30 is then threaded onto the split ring Ztia and adjusted so that when the slitter knife 10 is then slipped over the arbor and up against the face of the nut 39 it will be properly positioned axially on the arbor.

The split ring 20b is then positioned on the arbor on the opposite side of the slitter knife from the split ring 20a in a reversed or mirror image position with respect to the split ring 24in so that the hand threads of the split ring 2% are of the opposite hand from those of split ring 20a. The selection of the hand of threads will be described presently. A second nut 34 is then threaded onto split ring 2% and a key 35 is inserted in a keyway 38 provided on the arbor 12 and engages the keyways 24 of both of the split rings 20a and 20b and key slot 49 provided in the slitter knife 10 to prevent rotation.

Since the threads on the two split rings are of opposite hand, rotation of both of the nuts 30 and 34 in one direction will move the nuts toward each other thus clamping tightly against the slitter heads ltl. Similarly, rotation of both of the nuts in the opposite direction will tend to move them away from the slitter thus loosening them. The split rings 20a and 2012 are positioned on the shaft to provide the proper hand threads so that when the arbor is rotated for slitting, the nuts 30 and 34 will tend to move together and tighten against the slitter. The rings 20:: and 20b are positioned as seen in FIGURE 1 with the ring 20a defining left-hand threads and the ring 2% defining right-hand threads so that when the arbor 12 is rotated in the direction indicated by the arrow, the nuts will tighten against the slitter knife. Of course if the arbor were to be rotated in the opposite direction, the ring 20:! would be reversed to provide right-hand threads and the ring 202; would also be reversed providing left-hand threads.

From the foregoing description it is obvious that one of the outstanding advantages of this invention is that once the slitter head is positioned on the arbor and the arbor is rotated, the rotational movement of the arbor will tend to move the nuts together thus maintaining the slitter head exactly in its preselected position and tightly clamped in this position by the nuts. With prior art devices rotation of the arbor in either direction would tend to move both the nuts in the same direction axially on the shaft which would thus cause one nut to loosen away from the slitter head and the other to tighten against it. This would cause the slitter head to loosen and tend to move axially along the arbor.

Another outstanding feature of this invention is the attainment of the precise axial adjustment of the slitter head on the arbor. The split ring 20a is positioned in the approximate position for locating the slitter knife 11 The nut 39 is then threaded onto first split ring 2th: and it is freely rotatable thereon so that its adjustment on this split ring will provide for an exact positioning of the slitter knife with Vernier adjustment-s being possible by rotation of this nut. The split ring, which is providing the threads, is precluded from axial movement by the lands engaging the grooves 14 and is prevented from rotational movement by the key 36. Once this precise adjustment of the slitter knife is attained the other split ring Ztib is mounted on the opposite side of the slitter head. The nut 34 is then screwed onto the split ring 20b and clamped snugly against the slitter knife. Thus, with the device of this invention the exact position of the slitter head axially on the arbor is attained and once this position is selected it is positively retained in this position by the tightening tendencies of the nuts induced by rotation of the arbor for slitting.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claim.

I claim:

Means for mounting annular slitter knives and the like on arbors, characterized by attainment and maintenance of precise axial adjustment of said knives and the like on said arbors, said means comprising:

(a) an arbor provided with a plurality of circumferential grooves extending therearound and a keyway therealong, said grooves being distributed along the axis of the arbor for a sufficient length thereof to permit mounting of the slitter knife at variable selected positions axially along the arbor;

(b) a key for said keyway;

(c) an annular slitter knife adapted to slip over said grooved arbor, said knife having a keyway adapted to engage said key;

(d) a pair of annular split rings with internal grooves and keyways adapted to engage said arbor circumferential grooves and said key, said rings being adapted to positioning upon said arbor, on opposite sides of said knife, whereby said knife is approximately located along said arbor, said rings having external threads of opposite hand; and

(e) a pair of nuts with threads of opposite hand adapted to engage said externally threaded split rings and be clamped snugly against said slitter knife.

References Cited in the file of this patent UNITED STATES PATENTS 

